Method of hardening clockwork pivot-holes.



G. GRIVOLAS.

METHOD or HABDENING cLooKwonK PIVOT HOLES.

Patented Mar.' 23, 1909.v

.SLPPLIOATION 1`ILED JAN. 17, 1908.

FIG, 1.

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CLAUDE GRIVOLAS, OF ST. CLOUD, FRANCE.

METHOD OF HARDENING- CLOGKWORK PIVOT-HOLES.

specification of Letters Patent.

Patented March 23, 1909.

Application ied January 17, 1908. Serial No. 411,351.

meter movements and t ie like have hitherto' usually been made bydrilling the metal plate, usually of brass, which is to support thepivot, and making at one end or orifice of the erforation ahemispherical enlargement for t e reception of a small quantity oflubricant. Owing to the small degree of hardness of the metal used themetal is rapidly worn away and the holes become untrue, in

volving eccentricity of the pivots. VIt has been proposed to obviatethis disadvantage by using hard stones, such as rubies, in the holes,but the high price of these stones when they are of large size preventstheuse thereof in pendulum and meter movements and generally speaking inall clock movements of comparatively high power or low cost. V

I am aware that it is not broadly novel to compress or densify metalaround a hole for various purposes but the present invention provides amethod of hardening the plate, at the part where the pivot is to beplaced, by compressing the metal in a special way hereinafter fullydescribed and specifically pointed out in the claim so that themolecular condition thereof is modiiied at the said part.

The manner in which the method is carried into effect is illustrated inthe annexed drawing, in which- Figure 1 is an illustration of the firststage ofthe rocess, Figs. 2, 3 and 4 successive stages, ig. 5 thefinished product and Fig. 6 means for guiding the dies employed in theprocess, these iigures being diagrammatic sections. v

A is a plate usually of copper, with a pivothole A produced with the aidof a drill or unch. The plate A is then placed on the bed-plate of apress B with a steel die C having a steel projection D and a smallcircular ridge C which prevents slipping of the plate. The movable die Eof the press shaped to produce the cup-like recess A in the plate isalso of steel and has a hole E of the same diameter as the projection D.

The plate A is placed in the ress so that the projection D traverses theole A', and then the die E is lowered so that it strongly oompressesthemetal surrounding the hole A At the same time the ridge C is pressedinto the metal and by this means also coniines the compression to thepart adjacent the hole. The die E is then raised and the plate A removedfrom the press. Fig. 5 is a section showing the plate after thistreatment. The perforation is similar to an ordinary pivot-hole, but themetal between the circumference of the hole and the circular groove C isstrongly compressed and therefore better adapted to withstand wear.

In order that the movable die may always act perfectly vertically on theplate A, the plate F to which said die is iiXed may have four downwardlyprojecting guide rods G (Fig. 6) adapted to work in holes H provided inthe bed-plate B.

If desired a plurality of dies may be provided and so arranged that aplurality of pivot-holes can be simultaneously treated.

The method may be modified in such a way that'the compression isperformed before the late is perforated.

What I claim as my invention and desire to secure by Letters Patent ofthe United States is The method of hardening the plates of clockworksand meter movements and the like immediately about the pivot-holes bystrongly compressing the metal surrounding the holes and preventing thedispersal of said metal beyond a certain limit, said method consistingin forming a hole in the plate, placing the latter on a die having aprojection traversing said hole and a circular rib about saidprojection, to prevent slipping of the plate and confine the compressionand pressing a centrally perforated die on said plate so that theperforation engages the projection, substantially as described.

In witness whereof I have signed this speciiication in the presence oftwo witnesses.

CLAUDE GRIVOLAS.

